The present invention relates to an electronic component having an electric element sealed in a package, such as a SAW device, and electronic equipment having such an electronic component mounted on a substrate.
FIG. 7 is a top view of a conventional surface acoustic wave device (hereinafter referred to as a SAW device) and FIG. 8 is a side view thereof.
In a conventional SAW device, a surface acoustic wave element (hereinafter referred to as a SAW element) having an inter-digital transducer (hereinafter referred to as an IDT) formed on a piezoelectric substrate is housed in package 100 and an opening of package 100 is sealed with lid 102 using brazing material 101.
With a device of the above-mentioned structure, brazing material 101 sometimes protrudes on the periphery of package 100 when the opening of package 100 is sealed with lid 102.
When lid 102 is fixed to the opening of package 100, brazing material 101 provided between package 100 and lid 102 is heated and pressed from the top face of lid 102. The pressure protrudes brazing material 101 on a periphery of package 100 and forms ball-like clot 103. The ball-like clot 103 causes a deviation in the outside dimension of the SAW device, and hinders accurate mounting of the device onto a circuit board. In addition, such a clot poses another problem: falling of ball-like clot 103 may cause short circuits between neighboring electrode patterns or other components mounted.
It is an object of the present invention to provide an electronic component that has improved mounting accuracy and develops no short circuits on the circuit board. The component is provided with recesses for receiving surplus brazing material so that no brazing material protrudes on the periphery of the package when the opening of the package is sealed with the lid.
The electronic component in accordance with the present invention has recesses on side faces of its package for housing an electric element, in the direction from the top end to the bottom end of the package. On a surface of the recess, a metal layer that does not reach the bottom end of the package is formed. The metal layer has excellent wettability to a brazing material and helps the surplus brazing material flow into the recess easily. In addition, an interface between the top end face of the recess and the side face continues via a curved surface so that the brazing material easily flows into the recess.
With the structure in accordance with the present invention, the surplus brazing material flows into the recess when the opening of the package is sealed with a lid using the brazing material. This prevents the brazing material from protruding outside of the package and improves dimensional accuracy of the electronic component. Therefore, mounting accuracy of the electronic component can be improved and short circuits occurred in mounting the electronic component onto a substrate can be prevented. In addition, the recess having a curved cross sectional shape prevents the deterioration of the package strength.
Moreover, making the dimension of the lid smaller than that of the package prevents the brazing material from protruding outside of the package.
The electronic equipment in accordance with the present invention has the electronic component of the present invention mounted on a circuit board.